Hydraulic governor

ABSTRACT

A hydraulic engine governor wherein a throttle control valve also serves to establish a stable reference pressure independent of the system pump pressure for insuring stable governor operation. Stable reference pressure as determined by the throttle setting of the valve and a control pressure regulated by the centrifugal force exerted on a modulating valve as a result of the engine speed respectively, actuate the opposite ends of a piston to vary its position in accordance with the pressure differential. The piston position in turn regulates the amount of fuel injected into the engine to thereby provide a speed governing action. Provision is made for sealed communication for reference and control pressure to and from the rotary centrifugal modulating valve. The throttle valve features a control lever mechanism having minimized exposed control parts and which yet serves to retain the valve in throttle positions set by the operator.

[ Feb. 27, 1973 ilte St tent 1191 Gates et al.

[ HYDRAULIC GOVERNOR [75] Inventors: Marvin A. Gates, Chillicothe; John H. Parks, Peoria, both of Ill.

[73] Assignee: Caterpillar Tractor (30., Peoria, Ill.

[22] Filed: Sept. 18, 1970 [21] Appl. No.: 73,309

[52] US. Cl. ..123/140 FG, 123/140 R, 123/140 J, 123/140 A [51] Int. Cl "F 02d l/04 [58] Field of Search.....l23/140 R, 140 F6, 140, 140

[56] References Cited UNITED STATES PATENTS 2,384,340 9/1945 Reggio ..l23/l40.l

2,868,184 1/1959 Moulton..... ....123/l40.1

3,363,568 l/1968 Evans ..123/l40 R 3,557,765 1/1971 Nystrom ..l23/140 FG FOREIGN PATENTS OR APPLICATIONS Primary ExaminerLaurence M. Goodridge Assistant ExaminerRonald B. Cox Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio [5 7 ABSTRACT A hydraulic engine governor wherein a throttle control valve also serves to establish a stable reference pressure independent of the system pump pressure for insuring stable governor operation. Stable reference pressure as determined by the throttle setting of the valve and a control pressure regulated by the centrifugal force exerted on a modulating valve as a result of the engine speed respectively, actuate the opposite ends of a piston to vary its position in accordance with the pressure differential. The piston position in turn regulates the amount of fuel injected into the engine to thereby provide a speed governing action. Provision is made for sealed communication for reference and control pressure to and from the rotary centrifugal modulating valve. The throttle valve features a control lever mechanism having minimized exposed control parts and which yet serves to retain the valve in throttle positions set by the operator.

12 Claims, 8 Drawing Figures U HI\IDLE Z1 34. I LO IDLE PATENTEDFEBZTIQ'IB 7 1 7 SHEET 1 BF 6 24 59 U HI \IDLE 1 Lo IDLE INVENTORS MARVIN A. GATES JOHN H. PARKS BY yw f M7 1 'nw' ATTORNEYS PATENTEDFEBZUBYS 3,718,127,

:SHEET 2 0F 6 INVENTORS MARVIN A. GATES JOHN H. PARKS ATORNEYS Pmmwmw 3,718,127

sum 3 or 6 INVENTORS MARVIN A. GATES JOHN H. PARKS K j 9 C 1 W a l A'rmRNcYs PATENTE0FEB27I975 3,718,127

' SHEET HIF 6 INVENTORS MARVIN A. GATES JOHN H. PARKS ATTORNEYS PATENTEUFEBM 3,718,127

' SHEET 5 [IF e INVENTORS MARVIN A, GATES JOHN H, PARKS K 4-64 7 2 A'FI'ORNICS PATENTEDFEBW 5,718,127

SHEET 8. UF 6 INVENTORS MARVIN A. GATES JOHN H- PARKS K o. g 9; E 10/ ATTORNEYS BACKGROUND OF THE INVENTION Various governors are in use today for controlling the speed of an engine in compensatory relationship to the load imposed on the engine in order to maintain a substantially constant engine speed for a given throttle setting irrespective of fluctuations in the load. One such governor is disclosed in U.S. Pat. No. 3,472,215 to Maxwell et al. This patent is directed to a hydraulic governor wherein fluid pressure within a fuel pump housing is used as a reference pressure for a modulating valve of a centrifugal governor also contained within the housing. The modulating valve in turn establishes a control pressure regulated by the centrifugal force exerted on the valve as a result of engine speed. The control pressure acts in conjunction with a spring force on one end of a piston against the force of the reference pressure acting on the opposite end thereof to position the piston as a function of engine speed. The piston may be employed to position a sleeve metering device of a fuel injection pump, as described in U.S. Pat. No. 3,385,221 to Parks, to control the volume of fuel injected into the combustion or precombustion chambers of the engine in relation to engine speed, thereby providing a governing action.

However, a problem exists when using a governing system in the foregoing manner since high pressure surges are transmitted to the reference pressure by action of fuel injection pump plungers and the fuel transfer pump. As the reference pressure receives these pulses of high pressure, the governor tends to be unstable in operation. Another problem is encountered by virtue of the throttle control valve which, while establishing a reference pressure within the pump body, also bypasses fluid to a return line of the transfer pump. The control valve in being flow sensitive, is sensitive to changes in fuel viscosity resulting in changes to operating characteristics of the governor with variation in temperatures.

SUMMARY OF THE INVENTION The general object of the present invention is to provide an improved hydraulic governor of the basic type outlined hereinbefore which, however, is substantially insensitive to pressure surges and changes due to temperature variation in the fuel system pressure to thereby result in stable governor operation.

In the accomplishment of the foregoing and other objects and advantages of the invention, a governor is provided which includes a pressure reducing throttle control valve for developing a reference pressure for governor operation which is separate from fuel system pressure and substantially isolated from surges and variations therein. Means are provided to sealably communicate stable reference pressure to and engine speed representative control pressure from a centrifugal governor modulating valve, the reference pressure and control pressure being applied to opposite ends of a piston to vary the piston position in accordance with the pressure differential and thus with engine speed as compared to throttle setting. The piston position is in turn employed to regulate the amount of fuel injected into the precombustion or combustion chambers of the engine in relation to the pressure differential to thereby effect a governing action which tends to maintain engine speed constant for a given throttle setting. By virtue of the reference pressure being separate from system pressure, the governing action is not subjected to instabilities arising from variations in system pressure. In addition the throttle control valve is provided with an improved control lever mechanism which retains the valve in throttle positions manually set by the operator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic flow diagram of the overall hydraulic governor system of the present invention.

FIG. 2 is an elevational view with portions broken away of a fuel pump housing containing the governor depicting particularly the centrifugal modulating valve assembly and a fuel pump injection plunger thereof.

FIG. 3 is an enlarged view of a portion of the modulating valve assembly of FIG. 2.

FIG. 4 is a sectional view taken at line 4-4 of FIG. 2, illustrating particularly the fuel pump injection plunger pressure reducing throttle control valve of the governor.

FIG. 5 is a sectional view taken at line 5-5 of FIG. 2, illustrating particularly a face seal of the modulating valve and the fuel injection control piston of the governor.

FIG. 6 is a sectional view taken at line 6-6 of FIG. 5, and having portions broken away, illustrating particularly the control lever mechanism of the throttle control valve of the governor.

FIG. 7 is a sectional view taken at line 7 7 of FIG. 6, illustrating particularly the throttle control lever mechanism and an initial engine start-up speed limiting device that may be employed with the governor.

FIG. 8 is a sectional view taken at line 8-8 of FIG. 6, illustrating further details of the throttle control lever mechanism.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. 1 in detail, a fuel transfer pump 11 receives fuel from a tank and filter 12 through a check valve 13 and delivers the fuel via passage 14 to a chamber 16 within a pump housing 17. Chamber 16 also communicates via a passage 18, with a priming pump 19 having check valved inlet and outlet ports 21 and 22 for the purpose of charging the chamber with fuel prior to starting. Fuel from the chamber 16 is delivered to the precombustion or combustion chambers of an engine in amounts controlled by a fuel injection metering mechanism, as generally designated at 23. The pump 11 also delivers fuel to a throttle control valve assembly 24 via a cavity 26.

A pressure P1 is established in chamber 16 and cavity 26 by a bypass valve 27. This system pressure P1 is subject to pressure surges and variations due to the action of the transfer pump 11, plungers of the injection pump metering mechanism 23, and the like. Consequently, where the system pressure has been heretofore employed as a reference pressure for operation of a hydraulic governor, instabilities in the governing action have arisen due to the reference pressure fluctuations.

The foregoing difficulties are overcome with the governor system of the present invention in that the throttle control valve assembly 24 is arranged to develop a reference pressure P2 which is separate from the system pressure P1 and not subject to the fluctuations therein. The reference pressure P2 is determined by the setting of a manually adjustable throttle control lever 28 associated with the valve assembly 24.

The reference pressure is delivered via a passage 29 to a chamber 31 where it acts upon a face 32 of a piston 33. The reference pressure P2 is also delivered from throttle valve assembly 24 via passage 34 to a centrifugal modulation valve assembly 36 to serve as a reference pressure for operation thereof. The modulation valve assembly functions to develop a control pressure P3 which is representative of engine speed. The control pressure is transmitted via a passage 37 to a chamber 38 where it acts upon a face 39 of piston 33 opposite face 32. It is of importance to note that the entire system comprised of the outlet portion of throttle valve assembly 24, modulation valve assembly 36, and chambers 31 and 38 enclosing the opposite end faces of piston 33, is sealed and isolated from the system pressure P1.

The position of piston 33 is thus determined by the differential between the control pressure P3 and reference pressure P2. A lever 41 coupled to the piston serves to actuate the fuel injection pump metering mechanism 23 in accordance with piston position and thus the pressure differential. The mechanism is so arranged that the amount of fuel injected into the engine is in relation to the pressure differential to provide a governing action which tends to maintain a substantially constant engine speed for a given setting of the throttle control lever 28 of throttle valve assembly 24.

Considering now in more detail the throttle valve assembly 24 and referring to FIG. 4, it is to be noted that the assembly includes a valve member 42 slidable within a bore 43 of a housing 44. The valve member is formed with a central annular groove 46 which thereby defines enlarged portions 47 and 48 at the opposite ends thereof. A passage 49 extends through the face of end portion 47 into communication with the groove 46. The valve member is urged upwardly in the bore 43 by means of a spring 51 acting between a face of a control sleeve 52 positioned in the lower end of the bore and the face of end portion 48.

System pressure P1 in cavity 26 is transmitted via a passage 53 extending through housing 44 to bore 43. When the valve member is positioned such that groove 46 is opposite passage 53, the pressure P1 is delivered to the groove and communicated through passage 49 to a chamber 54 defined between the face of enlarged end portion 47 and the upper end of bore 43. As pressure builds up in chamber 54 the pressure urges the valve member downwardly against the force of spring 51 until enlarged end portion 47 blocks passage 53.

The reference pressure P2 is thus established in chamber 54 and it is to be noted that such pressure is isolated from system pressure Pl by virtue of the passage 53 being blocked. The reference pressure is at this time also existent in the annular groove 46 by virtue of the communication provided by passage 53. A passage 56 through the housing 44 at a position to communicate with the groove 46 when the valve member blocks passage 53 serves to transmit the reference pressure P2 to a cavity 57 which is in turn communicated with the passages 29 and 34 previously mentioned with reference to FIG. 1.

it is to be noted that the throttle control lever 28 is coupled in a manner subsequently described to the control sleeve 52 to move same upwardly or downwardly, thereby increasing or decreasing the spring force acting on the valve member 42. If the lever is moved in the direction of a high idle position, the spring force is increased and becomes greater than the reference pressure P2 at that time existing in chamber 54, the valve member 42 is urged upwardly, thereby exposing annular groove 46 to the system P1 in passage 53. The reference pressure P2 is thus permitted to increase to a value sufficient to overcome the spring force and urge the valve member downwardly to again block passage 53.

If the lever is moved in the direction of a low idle or shutoff position, the spring force is decreased such that the reference pressure P2 in chamber 54 urges the valve member 42 downwardly to expose a passage 58 to the groove 46. Passage 58 communicates with a return cavity 59 coupled to a fuel return line 61 (see FIG. 1). Thus, the passages and cavities containing reference pressure P2 are in communication with the fuel return line which is substantially zero pressure. The reference pressure thus decreases to an extent that the spring force is able to move the valve member upwardly to a position wherein enlarged end portion 48 again blocks passage 58, at which time the reference pressure is at a new reduced value. Thus, the reference pressure P2 is determined by the setting of the throttle control lever 28.

Referring now to FIGS. 2, 3 and 5 in particular detail, the centrifugal modulation valve assembly 36 will be seen to be of generally conventional design except that same is modified to permit sealed communication of reference pressure P2 and control pressure P3 to and from the assembly. More particularly, the passage 34 containing reference pressure P2 is formed in a cover 62 of the pump housing 17 secured at a position in confronting relation to the circular rotatable housing 63 of the modulating valve.

Passage 34 communicates with a passage 64 in a face seal 66 secured to the pump housing 17 in abutting relation to the end face of the rotatable housing 63 and locked against rotation. Passage 64 communicates with an annular groove 67 formed in the face of the rotatable housing. The groove is in turn communicated via a passage 68 in the rotatable housing with an annular groove 69 of a valve 71 slidable in a radial bore 72 provided in the housing. Rotation of housing 63 by a cam shaft 73 centrifugally urges the valve 71 outwardly causing a land 74 of the valve to uncover a passage 76 leading to a groove 77 formed in the face of the rotatable housing.

Fluid pressure acting in a chamber 78 at the outer end of the bore 72 urges the valve 71 inwardly against the centrifugal force of the rotatable housing until passage 76 is again blocked by land 74, thereby establishing the control pressure P3 in chamber 78 which is representative of engine speed. The control pressure P3 also exists in passage 76 and groove 77. The control pressure is transmitted to chamber 38 through a passage 79 in seal 66 and a passage 81 formed in the cover 62. Thus, in the foregoing manner reference pressure P2 and control pressure P3 are continuously supplied to and from the rotatable housing of the modulating valve assembly 36.

Considering now in more detail the piston 33 and its actuation of the fuel injection pump metering mechanism 23, the reference pressure P2 in chamber 31 acting upon the face 32 of the piston urges same downwardly against the force of reference pressure P3 in chamber 38 and a spring 82 disposed between piston face 39 and a face of a housing 83 until a balance of forces has been reached. The piston consequently assumes a position which is dependent upon the differential between the reference pressure P2 and control pressure P3. The piston correspondingly positions the lever 41 which is secured at one end to a rotary shaft 84.

In this regard, the free end of the lever is provided with a laterally projecting pin 86 which engages an annular groove 87 formed in the piston 33, as best shown in FIG. 5. Upward movement of the piston in response to increasing control pressure P3 with respect to the throttle reference pressure P2 thus effects counterclockwise rotation of shaft 84. Conversely downward movement of the piston in response to decreasing control pressure P3 with respect to reference pressure P2 effects clockwise rotation of shaft 84.

As best shown in FIGS. 2 and 4, rotation of shaft 84 causes a rotating member 88 to adjust a sleeve 89 slidable on a pump plunger 91 which determines the amount of fuel delivered to the engine as described in US. Pat. No. 3,385,221. It should be noted that counterclockwise rotation of the shaft 84 is effective to decrease the amount of fuel delivered to the engine whereas clockwise rotation is effective to increase the amount of fuel. Thus if the pressure differential P3/P2 decreases due to an increase in engine speed or a reduction in throttle setting, the amount of fuel injected is decreased to thus reduce engine speed. On the other hand, if the differential P3/P2 increases clue to a decrease in engine speed or increase in the throttle setting, the amount of fuel is increased to thus increase the engine speed.

Considering now a preferred throttle control lever mechanism associated with lever 28 to vary the reference pressure P2 in accordance with throttle setting, as best shown in FIGS. 6-8, the lever 28 is secured to a shaft 92 which is mounted for rotation in housing 17 adjacent housing 44 of throttle control valve assembly 24. Rotation of shaft 92 by means of the control lever 28 moves a lever 93 also secured to the shaft and having a pin 94 which rides in a slot 96 of the control sleeve 52 of valve assembly 24. Rotation of the shaft in a clockwise direction urges the sleeve upwardly to effect an increase in reference pressure P2 in the manner previously described. Conversely, rotation of the shaft in a counterclockwise direction urges the sleeve downwardly to effect a decrease in reference pressure P2.

To facilitate retention of the lever 28 in various idle positions the control lever mechanism further includes a pair of levers 97 and 98 which are pivotal about shaft 92. A third lever 99 is secured to the shaft for rotation therewith and interposed between levers 97 and 98. The levers 97, 98 and 99 are brought into lateral abutment with one another by means of a spring 101 disposed between a cover 102 traversed by the shaft and the outer side face of lever 97.

The shaft 92 may be rotated clockwise until a surface 103 of lever 99 strikes a high idle adjusting screw 104 threaded into the housing 17 to establish a high idle speed for the engine. When shaft 92 is rotated counterclockwise, a ball 106 disposed in a hole through lever 99 and slidable in arcuate slots 107 of levers 97 and 98 is moved upwardly until the ends of the slots are engaged by the ball. The position of the ends of the slots is determined by a low idle adjusting screw 108 which is threadably secured to a pin 109 transversely secured between the free ends of levers 97 and 98. The head of the adjusting screw 108 abuts the bottom portion of a cover 109 and a spring 111 coaxially disposed on the screw and acting between the cover and pin 109 resiliently retains the screw head in abutting position. Adjustment of the screw thus moves the levers 97 and 98 up or down to position the upper ends of the slots 107.

The control lever 28 and shaft 92 are retained in positions intermediate high and low idle by virtue of the lever 99 resiliently abutting the levers 97 and 98. Moreover, to move to a complete shut-off condition, shaft 92 is rotated in the counterclockwise direction beyond the low idle position determined by adjustment screw 108. This causes ball 106 to spread levers 97 and 98, permitting further rotation of the shaft and downward movement of sleeve 52 to decrease the reference pressure P2 to the extent that engine cutoff occurs.

It is to be noted that when initially starting the engine it is usually preferable to limit the speed of the engine until sufficient lubrication is available. For this reason it is preferable that a speed limiting control be used with the governor of the present invention. When the governor is set in a shut-off position, sleeve 52 has uncovered a passage 112 which communicates with return cavity 59 through passage 58. In this position, sufficient pressures cannot be developed and the engine cannot be started. To start the engine, sleeve 52 is moved upwardly to close passage 112. The position of sleeve 52 on initial start could normally allow sufficient pressure to build up where the engine would accelerate to high idle immediately with initial start. However, use of the previously referenced speed limiting device prevents such occurrence.

As shown in FIGS. 1 and 7, the speed limiting device is generally designated at 113 and basically includes a spring-loaded ball check 114 which prohibits the communication of transfer pump pressure in a cavity 116 with a passage 117 connected to return passage 58. With initial start of the engine the ball check acts as a primary bypass which would open at a lower pressure than the system bypass valve 27. System pressure Pl would thus be much lower than normal regardless of the setting established by sleeve 52. With pressure Pl limited to a predetermined low value, pressures P2 and P3 are correspondingly lower which thus limit the speed of the engine to a value which will prevent damage until sufficient lubrication has been established in the engine.

With the engine running, oil pressure increases and an oil pressure line connected to a passage 118 communicates with a face of a diaphragm 119. As oil pressure increases, the diaphragm is urged in a direction to compress the ball check spring 121 permitting pressure Pl to increase because of the increasing spring load. When proper engine oil pressure has been reached the diaphragm has forced the ball check to a position where further communication of transfer pump pressure between cavity 116 and passage 117 is prohibited. The operating value of pressure P1 is then established by the bypass valve 27 and the speed of the engine will be that established by the position of sleeve 52 and valve assembly 24 which controls reference pressure P2.

Considering now the overall operation of the governor under conditions other than those just described during engine start up, assume throttle control lever 28 to be in its full clockwise high idle position determined by lever 99 abutting high idle adjusting screw 104. Pressure P2 has been established at a somewhat lower value than system pressure P1 and the fuel pump metering sleeves 89 have been positioned on the pump plunger 91 to obtain a high idle speed for the engine. If

an increased load is placed on the engine, engine speed will tend to decrease unless more fuel is supplied to the engine. However, the pressure P3 in chamber 78 of the rotary housing 63 of the modulating valve assembly 36 acting on valve 71 will then become greater than the centrifugal force acting on the valve such that it will be moved inwardly. Pressure P3 which has been established in chamber 38 and acts upon the piston 33 will then dump through passage 76 to an annular groove 122 formed in the valve 71 which is open to return passages through a passage 123 (see FlG.- 3). With pressure P3 reduced in chamber 38, pressure P2 will force the piston 33 downwardly to increase the amount of fuel being delivered to the engine. With an increased amount of fuel being delivered to the engine, engine speed will stop decreasing. The position of the piston under these conditions when the design full load is placed on the engine is referred to as the full load speed of the engine and is the normal operating speed thereof.

When a decreased load is applied to the engine, enginc speed will increase because more fuel is being injected into the engine than what is needed for the decreased load. As engine speed increases,.the centrifugal force acting on the valve 71 will move it outwardly against the pressure of P3 in chamber 78 permitting pressure P2 to be in communication with passage 76, thus increasing pressure P3. As pressure P3 increases in chamber 38, piston 33 is moved upwardly against pressure P2 in chamber 31. Upward movement of the piston effects rotation of shaft 84 to move the metering sleeves of the injection pump to a decreased fuel position. When the full load speed has been regained, pressure P3 is of a value which is able to return valve 71 back to a position which closes passage 76 and prohibits it from communicating with pressure P2.

Although the invention has been hereinbefore described and illustrated in the accompanying drawings with respect to a preferred embodiment, it will be appreciate the numerous changes and modifications may be made therein without departing from the true spirit and scope of the invention, and thus it is not intended to limit the invention except by the terms of the following claims.

What is claimed is:

l. A hydraulic engine governor comprising a pump housing, fuel transfer pump means for establishing a system fuel pressure within said housing, fuel injection pump metering means for controlling the amount of fuel delivered to an engine from said housing, a manually operable pressure reducing throttle control valve disposed within said housing, said valve having an inlet and outlet and including means responsive to the outlet pressure to throttle the inlet pressure whereby the same will receive said system pressure and develop a separate and isolated reference pressure therefrom in accordance with a manually adjustable throttle setting of said valve, a centrifugal modulating valve disposed within said housing for receiving said reference pressure and developing a control pressure representative of engine speed, first and second sealed chambers having a movable piston disposed therein with opposite end faces of the piston respectively exposed to said first and second chambers, means for sealably transmitting said reference pressure from said throttle control valve to said modulating valve and said first chamber and said control pressure from said modulating valve to said second chamber, said piston being thereby positioned in accordance with the differential between said control pressure and reference pressure, and means coupling said piston to said injection pump metering means to determine the amount of fuel delivered therefrom in accordance with the position of said piston.

2. A hydraulic engine governor according to claim 1, further defined by said throttle control valve comprising a valve housing disposed within said pump housing, said valve housing have a bore therein, a valve member slidable within said bore and having a central annular groove defining enlarged portionsat the opposite ends of said valve member, said valve member having a passage extending through the end face of a first of said enlarged portions into communication with said groove, a spring acting upon the end face of the second of said enlarged portions to urge the valve member in the direction of a reference pressure chamber defined between an end of said bore and said first enlarged portion, throttle lever control means coupled to said spring for varying the spring bias thereof in accordance with manually adjustable throttle settings of said lever control means, means defining first, second, and third passages in said throttle valve housing communicating with said bore, said passages being disposed such that said first and second ones thereof are blocked by said first and second enlarged portions while the third one thereof is communicated with said groove in a first position of said valve member, said valve member being movable to a second position under the bias of said spring wherein said first and third passages are communicated with said groove, said valve member being movable to a third position under pressure developed in said reference pressure chamber wherein said second and third passages are communicated with said groove, means communicable connecting said first passage to said system pressure, means communicably connecting said second passage to a return line for system pressure, and means communicably connecting said third passage to said modulating valve and said first cavity.

3. A hydraulic engine governor according to claim 1, further defined by said modulating valve including a rotatable housing having a first passage for transmission of said reference pressure thereto and a second passage for transmission of control pressure therefrom, said rotatable housing having an end face with first and second annular grooves respectively communicating with said first and second passages, a face seal disposed in abutting relation to said face of said rotatable housing and secured against rotation therewith, said seal having first and second passages respectively communicating with said first and second annular grooves in said rotatable housing, and means sealably communicating said first and second passages of said face seal with respectively the reference pressure from said throttle control valve and said second chamber.

4. A hydraulic governor according to claim 2, further defined by said modulating valve including a rotatable housing having a first passage for transmission of said reference pressure thereto and a second passage for transmission of control pressure therefrom, said rotatable housing having an end face with first and second annular grooves respectively communicating with said first and second passages of said rotatable housing, a face seal disposed in abutting relation to said face of said rotatable housing and secured against rotation therewith, said seal having first and second passages respectively communicating with said first and second annular grooves in said rotatable housing, and means sealably communicating said first and second passages of said seal with respectively said third passage of said throttle valve housing and said second chamber.

5. A hydraulic governor according to claim 2, further defined by said throttle lever control means including a control sleeve slidable within the proximal end of said bore with respect to said second enlarged portion of said valve member, said sleeve acting upon the opposite end of said spring from that acting upon said second enlarged portion, a manually operable throttle control lever, and means coupling said control lever to said sleeve for translating the latter in response to rotation of the fonner between different throttle setting positions.

6. A hydraulic governor according to claim 5, further defined by the means coupling said control lever to said sleeve comprising a shaft journalled for rotation in said pump housing at a position adjacent said throttle valve housing, said throttle control lever secured to an exterior end of said shaft for rotation therewith, a second lever secured to said shaft for rotation therewith, a pin projecting transversely from the free end of said lever, said sleeve having a groove engaged by said pin, and

means for restraining said levers and shaft at predeter-,

mined positions of rotation thereof.

7. A hydraulic governor according to claim 6, further defined by the restraining means comprising a third lever secured to said shaft for rotation therewith, fourth and fifth levers mounted for rotation about said shaft on opposite sides of said third lever, means spring loading said third, fourth, and fifth levers into resilient lateral abutment with one another, a high idle adjusting screw positioned to engage a face of said third lever upon rotation of said shaft in a first direction, a bridge pin transversely connecting the free ends of said fourth and fifth levers, a low idle adjusting screw threadably secured to said bridge pin to adjustably rotate said fourth and fifth levers upon said shaft, means defining arcuate slots in the opposed side faces of said fourth and fifth levers, and a ball carried by said third lever and slidable in said slots, said ball engaging an end of said slots upon rotation of said shaft in a second direction opposite said first direction to determine a low idle position of said shaft, said ball spreading said fourth and fifth levers to permit further rotation of said shaft in said second direction beyond said low idle position.

8. A hydraulic governor according to claim 5, further defined by said modulating valve including a rotatable housing having a first passage for transmission of said reference pressure thereto and a second passage for transmission of control pressure therefrom, said rotatable housing having an end face with first and second annular grooves respectively communicating with said first and second passages of said rotatable housing, a face seal disposed in abutting relation to said face of said rotatable housing and secured against rotation therewith said seal having first and second passages respectively communicating with said first and second annular grooves in said rotatable housing, and means sealably communicating said first and second passages of said seal with respectively said third passage of said throttle valve housing and said second chamber.

9. A hydraulic governor according to claim 8, further defined by the means coupling said control lever to said sleeve comprising a shaft journalled for rotation in said pump housing at a position adjacent said throttle valve housing, said throttle control lever secured to an exterior end of said shaft for rotation therewith, a second lever secured to said shaft for rotation therewith, a pin projecting transversely from the free end of said lever, said sleeve having a groove engaged by said pin, and means for restraining said levers and shaft at predetermined positions of rotation thereof.

10. A hydraulic governor according to claim 9, further defined by the restraining means comprising a third lever secured to said shaft for rotation therewith, fourth and fifth leyers mounted for rotation about said shaft on opposite sides of said third lever, means spring loading said third, fourth, and fifth levers into resilient lateral abutment with one another, a high idle adjusting screw positioned to engage a face of said third lever upon rotation of said shaft in a first direction, a bridge pin transversely connecting the free ends of said fourth and fifth levers, a low idle adjusting screw threadably secured to said bridge pin to adjustably rotate said fourth and fifth levers upon said shaft, means defining arcuate slots in the opposed sidefaces of said fourth and fifth levers, and a ball carried by said third lever and slidable in said slots, said ball engaging an end of said slots upon rotation of said shaft in a second direction opposite said first direction to determine a low idle position of said shaft, said ball spreading said fourth and fifth levers to permit further rotation of said shaft in said second direction beyond said low idle position.

11. A hydraulic governor according to claim 1, further defined by engine speed limiting means for reducing said system pressure upon start-up of said engine to correspondingly reduce said reference pressure and control pressure, said limiting means being operable to restore said system pressure to a normal operatspring force, said valve member being operable in response to development of said level of reference pressure to block flow of said system pressure to said throttle valve and thereby isolate said reference pres sure from said system pressure. 

1. A hydraulic engine governor comprising a pump housing, fuel transfer pump means for establishing a system fuel pressure within said housing, fuel injection pump metering means for controlling the amount of fuel delivered to an engine from said housing, a manually operable pressure reducing throttle control valve disposed within said housing, said valve having an inlet and outlet and including means responsive to the outlet pressure to throttle the inlet pressure whereby the same will receive said system pressure and develop a separate and isolated reference pressure therefrom in accordance with a manually adjustable throttle setting of said valve, a centrifugal modulating valve disposed within said housing for receiving said reference pressure and developing a control pressure representative of engine speed, first and second sealed chambers having a movable piston disposed therein with opposite end faces of the piston respectively exposed to said first and second chambers, means for sealably transmitting said reference pressure from said throttle control valve to said modulating valve and said first chamber and said control pressure from said modulating valve to said second chamber, said piston being thereby positioned in accordance with the differential between said control pressure and reference pressure, and means coupling said piston to said injection pump metering means to determine the amount of fuel delivered therefrom in accordance with the position of said piston.
 2. A hydraulic engine governor according to claim 1, further defined by said throttle control valve comprising a valve housing disposed within said pump housing, said valve housing have a bore therein, a valve member slidable within said bore and having a central annular groove defining enlarged portions at the opposite ends of said valve member, said valve member having a passage extending through the end face of a first of said enlarged portions into communication with said groove, a spring acting upon the end face of the second of said enlarged portions to urge the valve member in the direction of a reference pressure chamber defined between an end of said bore and said first enlarged portion, throttle lever control means coupled to said spring for varying the spring bias thereof in accordance with manually adjustable throttle settings of said lever control means, means defining first, second, and third passages in said throttle valve housing communicating with said bore, said passages being disposed such that said first and second ones thereof are blocked by said first and second enlarged portions while the third one thereof is communicated with said groove in a first position of said valve member, said valve member being movable to a second position under the bias of said spring wherein said first and third passages are communicated with said groove, said valve member being movable to a third position under pressure developed in said reference pressure chamber wherein said second and third passages are communicated with said groove, means communicable connecting said first passage to said system pressure, means communicably connecting said second passage to a return line for system pressure, and means communicably connecting said third passage to said modulating valve and said first cavity.
 3. A hydraulic engine governor according to claim 1, further defined by said modulating valve including a rotatable housing having a first passage for transmission of said reference pressure thereto and a second passage for transmission of control pressure therefrom, said rotatable housing having an end face with first and second annular grooves respectively communicating with said first and second passages, a face seal disposed in abutting relation to said face of said rotatable housing and secured against rotation therewith, said seal having first and second passages respectively communicating with said first and second annular grooves in said rotatable housing, and means sealably communicating said first and second passages of said face seal with respectively the reference pressure from said throttle control valve and said second chamber.
 4. A hydraulic governor according to claim 2, further defined by said modulating valve including a rotatable housing having a first passage for transmission of said reference pressure thereto and a second passage for transmission of control pressure therefrom, said rotatable housing having an end face with first and second annular grooves respectively communicating with said first and second passages of said rotatable housing, a face seal disposed in abutting relation to said face of said rotatable housing and secured against rotation therewith, said seal having first and second passages respectively communicating with said first and second annular grooves in said rotatable housing, and means sealably communicating said first and second passages of said seal with respectively said third passage of said throttle valve housing and said second chamber.
 5. A hydraulic governor according to claim 2, further defined by said throttle lever control means including a control sleeve slidable within the proximal end of said bore with respect to said second enlarged portion of said valve member, said sleeve acting upon the opposite end of said spring from that acting upon said second enlarged portion, a manually operable throttle control lever, and means coupling said control lever to said sleeve for translating the latter in response to rotation of the former between different throttle setting positions.
 6. A hydraulic governor according to claim 5, further defined by the means coupling said control lever to said sleeve comprising a shaft journalled for rotation in said pump housing at a position adjacent said throttle valve housing, said throttle control lever secured to an exterior end of said shaft for rotation therewith, a second lever secured to said shaft for rotation therewith, a pin projecting transversely from the free end of said lever, said sleeve having a groove engaged by said pin, and means for restraining said levers and shaft at predetermined positions of rotation thereof.
 7. A hydraulic governor according to claim 6, further defined by the restraining means comprising a third lever secured to said shaft for rotation therewith, fourth and fifth levers mounted for rotation about said shaft on opposite sides of said third lever, means spring loading said third, fourth, and fifth levers into resilient lateral abutment with one another, a high idle adjusting screw positioned to engage a face of said third lever upon rotation of said shaft in a first direction, a bridge pin transversely connecting the free ends of said fourth and fifth levers, a low idle adjusting screw threadably secured to said bridge pin to adjustably rotate said fourth and fifth levers upon said shaft, means defining arcuate slots in the opposed side faces of said fourth and fifth levers, and a ball carried by said third lever and slidable in said slots, said ball engaging an end of said slots upon rotation of said shaft in a second direction opposite said first direction to determine a low idle position of said shaft, said ball spreading saiD fourth and fifth levers to permit further rotation of said shaft in said second direction beyond said low idle position.
 8. A hydraulic governor according to claim 5, further defined by said modulating valve including a rotatable housing having a first passage for transmission of said reference pressure thereto and a second passage for transmission of control pressure therefrom, said rotatable housing having an end face with first and second annular grooves respectively communicating with said first and second passages of said rotatable housing, a face seal disposed in abutting relation to said face of said rotatable housing and secured against rotation therewith said seal having first and second passages respectively communicating with said first and second annular grooves in said rotatable housing, and means sealably communicating said first and second passages of said seal with respectively said third passage of said throttle valve housing and said second chamber.
 9. A hydraulic governor according to claim 8, further defined by the means coupling said control lever to said sleeve comprising a shaft journalled for rotation in said pump housing at a position adjacent said throttle valve housing, said throttle control lever secured to an exterior end of said shaft for rotation therewith, a second lever secured to said shaft for rotation therewith, a pin projecting transversely from the free end of said lever, said sleeve having a groove engaged by said pin, and means for restraining said levers and shaft at predetermined positions of rotation thereof.
 10. A hydraulic governor according to claim 9, further defined by the restraining means comprising a third lever secured to said shaft for rotation therewith, fourth and fifth levers mounted for rotation about said shaft on opposite sides of said third lever, means spring loading said third, fourth, and fifth levers into resilient lateral abutment with one another, a high idle adjusting screw positioned to engage a face of said third lever upon rotation of said shaft in a first direction, a bridge pin transversely connecting the free ends of said fourth and fifth levers, a low idle adjusting screw threadably secured to said bridge pin to adjustably rotate said fourth and fifth levers upon said shaft, means defining arcuate slots in the opposed sidefaces of said fourth and fifth levers, and a ball carried by said third lever and slidable in said slots, said ball engaging an end of said slots upon rotation of said shaft in a second direction opposite said first direction to determine a low idle position of said shaft, said ball spreading said fourth and fifth levers to permit further rotation of said shaft in said second direction beyond said low idle position.
 11. A hydraulic governor according to claim 1, further defined by engine speed limiting means for reducing said system pressure upon start-up of said engine to correspondingly reduce said reference pressure and control pressure, said limiting means being operable to restore said system pressure to a normal operating level in response to engine oil pressure increasing to a normal operating level.
 12. A hydraulic governor according to claim 1, further defined by said throttle control valve including valve member means for permitting flow of said system pressure to said throttle valve to develop said reference pressure therein to a level balancing a predetermined spring force, said valve member being operable in response to development of said level of reference pressure to block flow of said system pressure to said throttle valve and thereby isolate said reference pressure from said system pressure. 